Tamoxifen is the oldest and most prescribed hormone therapy drug used to treat advanced breast cancer in men and women, and early estrogen receptor-positive (ER-positive) breast cancer in women.
It blocks the estrogen effects in the breast tissue, so doctors may also prescribe it to prevent breast cancer in women who are at a high risk because of age, family history, or other factors.
Until now, the drug has been a tablet taken daily by mouth. But researchers at Northwestern University announced today that a breakdown product of tamoxifen, called 4-OHT, applied as a gel on the breasts of women with ductal carcinoma in situ (DCIS), was as effective in reducing cell proliferation as oral tamoxifen, but with fewer side effects.
“Our data suggest that gel application of tamoxifen could replace the tablet form used by some women at high risk for breast cancer to prevent the development of the disease, and, thus encouraging more women to adhere to preventive therapy,” said Seema A. Khan, MD, professor of surgery at Northwestern University Feinberg School of Medicine.
While oral tamoxifen has been shown effective in treating some breast cancers, it won't work on hormone receptor-negative breast cancer. And the drug has a dark side.
Tamoxifen can cause a range of side effects from mild to life-threatening. Most common are menopausal symptoms — hot flashes, night sweats, vaginal dryness and mood swings — as well as nausea and depression in women.
Headaches, impotence and decreased sexual interest are common in men, according to the U.S. National Cancer Institute.
On the more serious side, the drug has been known to increase the risk of blood clots, most commonly in the lungs and legs, as well as increasing risk of stroke, cataracts, and endometrial and uterine cancers in women.
Khan and colleagues conducted a randomized, double-blind, placebo-controlled phase II clinical trial to compare the effects of 4-OHT gel applied on the breasts with those of tamoxifen taken orally.
Participants were 26 women between the ages of 45 to 86 years with a diagnosis of estrogen receptor-positive DCIS.